This invention relates generally to pressure compensated load responsive control valves of direction control type, which in control of a load, while using a control load pressure sensing passage, automatically maintain pump discharge pressure at a level higher, by a constant pressure differential, than the pressure required by the controlled load, by either bypassing excess pump flow to system reservoir, or by varying displacement of the pump.
In more particular aspects this invention relates to load responsive direction control valves having load sensing ports and a control regeneration position, in which the motor ports are connected to each other and to system pump.
In still more particular aspects this invention relates to load responsive direction control valves having load sensing ports and a control regeneration position in which the flow into connected motor ports is controlled proportionally to the displacement of spool in its regenerative position and independent of system pressure.
The direction control valves with regeneration position, in which motor ports are connected to each other and to system pump, while system reservoir is isolated, are well known in the art and have been used in conventional fluid power circuits for many years. Those valves in the regeneration position permit the free fluid transfer between, for example, piston rod end and piston end of a hydraulic cylinder. The pump then supplies only the difference between flow in and flow out of a cylinder. In this way a very much faster extension of the cylinder is achieved than that equivalent to supplying all of the pump flow into the inlet port of the cylinder. Those valves suffer from one basic disadvantage in that all of the pump flow has to be used in regeneration cycle, thus limiting the choice of maximum cylinder speed and preventing control of the cylinder speed.